Various types of general purpose robots which are driven by a servomotor, a servovalve and others and provided with a plurality of drive axes operated and controlled by a controller have been developed to exercise a great performance for saving labor, rationalization of working and other purposes. The robots include those of the cylindrical coordinate type robot, orthogonal coordinate type robot and horizontally articulated type robot which have a vertical drive axis and are capable of positioning the axis at an arbitrary point along a horizontal plane rectangular to the axis. Most of these robots are provided with an axis capable of turning a workpiece posture for arbitrarily handling the workpiece within a horizontal plane at the nose of an arm. There is also such a general purpose robot which has three moving axes for space locating and three moving axes for hand posture controlling. What is common to these robots is that there are provided means for locating a robot hand on an arbitrary point along a plane and another means for turning the hand in an arbitrary direction around an axis vertical to the plane.
If robots are provided with means for locating a workpiece at a point within a plane and another means for turning a workpiece posture freely on the plane, then the workpiece can be incorporated to various kind of members to be assembled, and thus a flexibility in assembling function of the robots are improved so high. This invention therefore relates to the robot controlling system as described hereinabove.
However, the system for controlling such robots with high flexibility as mentioned comprises merely a system of teaching playback in most cases, and the teaching work yet has many problems.
In an assembling robot system for which a high locating precision is required, it is very difficult to match an arm origin position to the installation standard position of a robot with the high locating precision mechanically, moreover it is also difficult to match a position of a table for installing the robot thereon, a supply equipment such as pallet or the like, and members disposed peripherally of the robot such as a substrate member to be assembled and the like with a locating precision required relative to the robot arm.
Under the existing circumstances of manufacturing robots and robot systems as described above, the system controlled only based on teaching playback requires repeated teaching operation with respect to the same operating position in the member with reference to operating positions and hand directions in the member even if the same system is manufactured more than one, and with respect to the same members placed at different places in the same system.
For the reason given above, a method has been already proposed in our Japanese Application No. 59-128953. The method comprises the steps of defining a local coordinate system in a member to be assembled so as to designate many operating positions in an assembled setup, setting the operating position in terms of a coordinate of the local coordinate system, specifying only the coordinate taken by a reference point of the local coordinate system in a robot absolute coordinate system according to teaching method or other steps, operating a robot at each operating position of the member to be assembled according to a coordinate transformation between the local and absolute coordinate systems. This invention is to provide a controlling system in which the above method is further improved.
An object of this invention is to simplify substantially the operation for specifying an operating position and a hand direction when operation is carried out at a plurality of operating positions of the same member to be assembled placed in a plurality of places in the same robot system.
Another object of this invention is to simplify indication of an operating position and a hand direction second robot system and so on when the same robot system is used as the second robot system.
A further object of this invention is to facilitate an off-line teaching operation according to CAD, CAM and the like.
A superiority of the operating point setting system according to the local coordinate system described above in the aforesaid Japanese Application No. 59-128953 is as follows:
Members to be assembled include a member like a printed circuit substrate, for example, which has many operating points exceedingly precise in positional relation with each other. For such parts, a technique according to an on-line teaching of each operating position must be rather avoided, and the operating position can be set precisely by far according to a numeric input or off-line teaching in terms of a coordinate of the local coordinate system arranged on the member with a reference point. Further, it is advantageous to set only a coordinate of a reference point of the local coordinate system in a robot absolute coordinate system, thereby carrying out an actual operation through coordinate transformation between the local and absolute coordinate systems.
The above method relates only to a coordinate of the operating position, however, a method effective to correct an angular direction of a part incorporated into the member has not been in practice until now. Including the angular direction of parts, this invention simplifies the operating point setting method in a local coordinate.
In order to facilitate CAD, CAM in application of the robot, the operating position and the hand direction can be given by numeric input or off-line teaching as a coordinate in the local coordinate system and as an angle relative to a standard or base axis of the local coordinate system as described above.